The Arabidopsis thaliana Dihydroxyacetone Phosphate Reductase Gene SUPPRESSOR OF FATTY ACID DESATURASE DEFICIENCY1 Is Required for Glycerolipid Metabolism and for the Activation of Systemic Acquired Resistance[W]

Abstract

Systemic acquired resistance (SAR) is a broad-spectrum resistance mechanism in plants that is activated in naive organs after exposure of another organ to a necrotizing pathogen. The organs manifesting SAR exhibit an increase in levels of salicylic acid (SA) and expression of the PATHOGENESIS-RELATED1 (PR1) gene. SA signaling is required for the manifestation of SAR. We demonstrate here that the Arabidopsis thaliana suppressor of fatty acid desaturase deficiency1 (sfd1) mutation compromises the SAR-conferred enhanced resistance to Pseudomonas syringae pv maculicola. In addition, the sfd1 mutation diminished the SAR-associated accumulation of elevated levels of SA and PR1 gene transcript in the distal leaves of plants previously exposed to an avirulent pathogen. However, the basal resistance to virulent and avirulent strains of P. syringae and the accumulation of elevated levels of SA and PR1 gene transcript in the pathogen-inoculated leaves of sfd1 were not compromised. Furthermore, the application of the SA functional analog benzothiadiazole enhanced disease resistance in the sfd1 mutant plants. SFD1 encodes a putative dihydroxyacetone phosphate (DHAP) reductase, which complemented the glycerol-3-phosphate auxotrophy of the DHAP reductase–deficient Escherichia coli gpsA mutant. Plastid glycerolipid composition was altered in the sfd1 mutant plant, suggesting that SFD1 is involved in lipid metabolism and that an SFD1 product lipid(s) is important for the activation of SAR.

Plastidial fatty acid levels regulate resistance gene-dependent defense signaling in Arabidopsis

“…Our earlier work has shown that a mutation in the SSI2-encoded S-ACP-DES affects many cellular responses in the plant, and we have demonstrated that the altered defense-related phenotypes in ssi2 plants are specifically associated with their low 18:1 levels (12,(15)(16)(17)22). Previous research by Nandi et al (37,38) has implicated a reduction in hexadecatrienoic acid (16:3) to be responsible for restoration of ssi2 phenotypes. However, several results contradict a role for 16:3.…”

Plant immunity: the EDS1 regulatory node

“…Several specific findings are worth highlighting. First, SUPPRESSOR OF FATTY ACID DE-SATURASE 1 (SFD1), a dihydroxyacetone phosphate reductase that is involved in glycerolipid metabolism [42 ], and DEFECTIVE IN INDUCED RESIS-TANCE1 (DIR1), a putative lipid transfer protein [43], contribute to the establishment of systemic resistance. EDS1 and PAD4 are also necessary for the establishment of SAR (L Jorda, A Maldonado, J Parker, C Lamb, unpublished).…”

Loss of the Transit Peptide and an Increase in Gene Expression of an Ancestral Chloroplastic Carbonic Anhydrase Were Instrumental in the Evolution of the Cytosolic C4 Carbonic Anhydrase in Flaveria

“…Wang et al (2009) have suggested that these two roles may be linked, as evidence exists for plant defense pathways being regulated by lipidbased signals (Nandi et al, 2004;Chandra-Shekara et al, 2007).…”